We found 27 dictionaries that define the word ppb:

General (12 matching dictionaries)

1. ppb: Merriam-Webster
2. ppb: Oxford Learner's Dictionaries
3. ppb: American Heritage Dictionary of the English Language
4. ppb: Wordnik
5. PPB, ppb: Wiktionary
6. ppb: Webster's New World College Dictionary, 4th Ed.
7. ppb: The Wordsmyth English Dictionary-Thesaurus
8. PPB: Infoplease Dictionary
9. p.p.b, ppb: Dictionary.com
10. PPB: Wikipedia, the Free Encyclopedia
11. PPB: Stammtisch Beau Fleuve Acronyms
12. ppb: TheFreeDictionary.com

Business (1 matching dictionary)

13. Glossary of Crop Abbreviations (No longer online)

Medicine (3 matching dictionaries)

14. ppb: Merriam-Webster Medical Dictionary
15. online medical dictionary (No longer online)
16. ppb: Medical dictionary

Miscellaneous (2 matching dictionaries)

17. PPB: Acronym Finder
18. AbbreviationZ (No longer online)

Science (3 matching dictionaries)

19. PPB: Material Safety Data Sheets HyperGlossary
20. ppb: Extragalactic Astronomy
21. PPB, ppb: A Dictionary of Quaternary Acronyms and Abbreviations

Slang (1 matching dictionary)

22. PPB: Urban Dictionary

Tech (5 matching dictionaries)

23. PPB: GEOGRAPHIC INFORMATION SYSTEMS, CARTOGRAPHY, AND REMOTE SENSING
24. Google, News, Images, Wikipedia, Reddit, BlueSky